Though the Safari 4 beta added a lot, at least in looks, when compared to earlier developer betas, one notable thing it lost was the “Save as Web Application…” command in the File menu. Using this command, Safari would make an application in your Applications folder that basically ran just that one website, something introduced to the masses with a piece of freeware called Fluid. However, this feature is not gone, nor have plans for it stalled. It seems to just been have removed from the public.
It looks like all that’s been removed is the menu command. Looking inside Safari’s package contents (right click, “Show Package Contents”) all the files for the web application icons are intact, as is “WebApplicationCore.bundle” with the web application’s core files. What does this tell us? It seems to me that Apple doesn’t want this to be in the Public Beta, because it will come with Safari 4 for Mac when it is released along with Snow Leopard. This feature won’t be in the Windows version, because it’s creating applications, which will likely be Mac OS X only (though, if they put the work into making it make Windows web apps, too, that would be pretty cool.)
Other files found while poking around the Resources indicate that Apple may be planning to make tabs on top an option, that if you visit a suspected phishing site, Safari will display a warning page beforehand, and (exciting news for themers and tweakers like myself) almost all of the new interface elements are files in the Resources that are simple PNG files. I’m planning to start changing the tabs to my liking as soon as I’m done writing here.